Conventional chewing gum generally includes gum base, water-soluble flavoring and water-soluble sweenteners, for example, various sugars and/or artificial sweeteners such as sodium or calcium saccharin. Such gum initially provides a desirable strong sweet taste which declines rapidly during the first three to five minutes of chewing to a very slight perceptible level of sweetness and flavor. The result is that after about five minutes of chewing all that remains in the mouth is an essentially tasteless wad which provides little in the way of flavor, aroma or sweetness. Furthermore, chewing gum which depends upon the water-soluble forms of saccharin for its sweetness exhibits an undesirably strong sweet taste initially accompanied by an objectionable medicinal and/or bitter after-taste. Accordingly, there clearly is a need and long felt want for a chewing gum which possesses long-lasting flavor without the undesirable medicinal and bitter after-taste which normally accompanies chewing of gum sweetened by the soluble saccharin salts.
It has been found that the sweetness and flavor of non-sour flavored (mint), fruit-flavored or sour chewing gum can be prolonged by incorporating a solid poorly extractable or poorly water-soluble sweetener in particulate form, such as a poorly water-soluble form of saccharin, and optionally, where sour or fruit flavors are desired, a poorly extractable or poorly water-soluble food acid in particulate form, in a chalk-free gum base during the preparation of the gum. The particulate poorly extractable or poorly water-soluble sweetener and food acid are substantially retained in the chalk-free gum base and during chewing undergo slow and controlled release into the saliva.
It is important in the above chewing gum that the free saccharin acid form of the poorly extractable, poorly water-soluble saccharin employed in one embodiment remain in the gum base for as long as possible without being solubilized therefrom. However, it has been found that where conventional gum base compositions, that is, those gum bases containing calcium carbonate (chalk) as a filler and/or texturizing agent are employed in forming the chewing gum, the chewing gum tends to lose its sweetness retention properties after a few weeks of shelf storage at room temperature. Apparently, during storage, the free acid form of saccharin reacts with the chalk in the gum base to form the calcium saccharin salt which is solubilized from the chewing gum substantially faster than the free acid form of saccharin. Thus, conversion of the free saccharin acid to a soluble salt such as the calcium or sodium salts of saccharin should be avoided where possible.